We are engaged in a case-control study of malignant melanoma. The study has been designed to permit simultaneous examination of multiple antecedent risk factors, including occupational and recreational exposure to sunlight, habits of protection against the sun, ethnicity, skin color, residential history, medical history and history of exposure to drugs and chemicals. Cases of malignant melanoma will be identified through the LAC/USC Cancer Surveillance Program. Controls will be neighborhood residents of the same age, sex and race. The questionnaire which has been designed to ascertain the above exposure, will be administered by personal interview to both cases and controls. Standard matched pair and non-matched group analyses will be performed on the data obtained.